Sensory games

Abstract

Electronic game apparatus comprising a board displaying discrete playing areas and a number of playing pieces. Transmit and receive coils are provided beneath the surface of the board, preferably at right angles to each other, and each playing piece is provided in its base with an element. Means are provided for supplying a high-frequency current to each transmit coil in turn and for detecting the voltage induced in the receive coils for each discrete playing area. The presence of a playing piece on the playing area being tested, will affect the voltage induced in the receive coils and hence the presence, absence or type if desired, of a playing piece may be determined. The element preferably consists of any suitable metal or ferromagnetic material. Playing pieces of different types may be provided with elements of different materials.

We claim: 
     
       1. An electronic game apparatus comprising; a board having discrete playing areas, a plurality of playing pieces, a plurality of transmit and receive coils arranged beneath the board, the playing pieces having an element, a supply means for supplying a current to the transmit coils to induce a voltage in the receive coils, and a comparison means for comparing the voltage with a reference voltage. 
     
     
       2. Apparatus according to claim 1 wherein the element of the playing pieces is comprised of metal. 
     
     
       3. Apparatus according to claim 1 wherein the playing pieces are comprised of first and second sets of playing pieces, the element of the first set comprising a material having a first conductivity and the element of the second set comprising a material having a second conductivity. 
     
     
       4. Apparatus according to claim 3 wherein the element of the first set comprises metal and the element of the second set comprises a material selected from the group of ferrite and finely divided ferromagnetic material. 
     
     
       5. Apparatus according to claim 1 wherein the reference voltage is the voltage in the receive coils, for each discrete playing area, in the absence of a playing piece. 
     
     
       6. Apparatus according to claim 1 wherein an offset is added to the reference voltage to avoid spurious detection responses. 
     
     
       7. Apparatus according to claim 1 wherein the supply means comprises an oscillator and a multiplexer to select the transmit coil to which the current is supplied. 
     
     
       8. Apparatus according to claim 1 in which the comparison means comprises a multiplexer to select the receive coil, a preamplifier to amplify the difference between the two voltages, a synchronous detector, an integrator and a comparator. 
     
     
       9. Apparatus according to claim 1 in which the transmit coils have a tuned circuit to match the impedances of a drive current supply circuit and the transmit coils. 
     
     
       10. Apparatus according to claim 1 wherein the transmit and receive coils are substantially parallel to the board and substantially perpendicular to each other.